In recent years, information technology-related devices and communication devices such as personal computers, video cameras, and mobile phones have rapidly become popular, and therefore importance is placed on the development of batteries (e.g., lithium batteries) excellent as power sources of such devices. Further, in industrial fields other than the fields of information technology-related devices and communications-related devices, for example, in the field of automobile industry, lithium batteries for use in electric cars and hybrid cars are being developed.
Conventional commercially-available lithium batteries use an organic liquid electrolyte containing a flammable organic solvent, and therefore need to have a safety device that suppresses temperature rise during short circuit and to be improved in structure and material to prevent short circuit. On the other hand, solid-state batteries using a solid electrolyte instead of a liquid electrolyte have no flammable organic solvent therein, and therefore their safety devices can be simplified. For this reason, it is believed that such solid-state batteries are advantageous in terms of production cost and productivity. Among various solid-state batteries, solid-state batteries using a sulfide solid electrolyte material are advantageous in that they have excellent Li ion conductivity.
Meanwhile, various conventional methods for processing used batteries which are past their useful lives are known. For example, Patent Document 1 discloses a method for processing a Na—S battery using a solid electrolyte, in which Na is melted in a hot liquefied wax and the melted Na is taken out of the battery. Further, Patent Document 2 discloses a method for separating, for example, Co and Cu contained in a used lithium battery from each other by utilizing factors such as the difference in magnetic properties between them. Further, Patent Document 3 discloses a method for separating and recovering Co and Li from an electrode material, in which the electrode material containing Co and Li is dissolved in sulfuric acid and then Co and Li are separated and recovered from insoluble matter. Further, Patent Document 4 discloses a method for efficiently separating and recovering valuable metals from a used lithium battery by using a solution such as an acidic solution.    Patent Document 1: Japanese Patent No. 3015423    Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. Hei 11-185833    Patent Document 3: JP-A No. 2003-27151    Patent Document 4: JP-A No. 2007-122885